I swear I don't make these things up, and I AM talking about neonates, not
older kids (who may have other things going on if they suddenly take up
digit or pacifier sucking).  I always thought it was probably habituation or
an infant with a strong sucking need , too.   And clearly, there are all
sorts of infants who are inappropriately "plugged" with pacifiers by parents
whose real agenda is to artificially shorten or delay feeds.  But why do
some kids become such vehement users of pacifiers or such compulsive thumb
suckers?

A group of Japanese ENTs, S. Mukai. C. Mukai, K. Asaoka and S. Nagasugi,
have studied this phenomenon extensively.  Linda Smith and I both got
interested in their work, and have both read quite a few of their papers,
which have appeared in respectable journals such as Annals of Oto Rhinol
Laryngol Suppl (1991) Annals Oto Rhinol Laryngol (1993).  They started
looking at kids with anklyloglossia (tongue-tie) and discovered they often
had other mid-line defects further down the line as it were:   deviations of
the epiglottis and larynx, with associated respiratory difficulties that
were so severe "[that] The signs and symptoms of this disease were very
similar to those observed in victims of sudden infant death syndrome before
thier death." (1991).

Further, "In our studies of ankyloglossia with deviation of the epiglottis
and larynx (ADEL), there were many babies who slept only when they were
thumb sucking.  Babies with ADEL have respiratory insufficiency.  We
supposed that thumb sucking was related to respiration.  To test this
hypothesis we monitored respiration during sleep with and without thumb
sucking.

Chest and eye movements, arterial blood saturation rate (SaO2) and pulse
rate (PR) were monitored in ten babies from four to ten weeks as they slept
while thumb sucking and abstaining from thumb sucking.  We compared apnea,
respiratory frequency and minimum level of SaO2 during three minute periods
before and after we pulled out fingers from babies.

Two out of ten subjects presented apnea three times in three minutes during
thumb sucking.  When not sucking, eight out of ten presented apnea an
average of 10.2 times in three minutes.  The average number of apnea
episodes while thumb sucking and without thumb sucking was 1.0 and 5.9
respectively. The average respiratory frequency was 8.0/10 sec. during thumb
sucking and 6.8/10 sec without sucking.  The average lowest level of SaO2
was 98.3 and 90.7 respectively.  There were significant differences between
respiratory frequency, (p=0.0075), length of apnea (p=0.0047), and minimum
SaO2 (p=0.030) during sleep with and without thumb sucking.

 We concluded that thumb sucking caused a relief from respiratory
insufficiency...The evidence suggests there is a sleeping respiratory center
and a feeding respiratory center.  As the sleeping respiratory center is not
fully mature in young infants, apnea and a decrease of SaO2 occurred during
sleep.  On the other hand, the feeding respiratory center matures in early
infancy, making it possible for the infant to maintain constant respiratory
rhythm and ventilation.  By this reasoning, we concluded that thumb sucking
compensates for respiratory insufficiency and is not merely a habit that
provides comfort but is in fact an intrinsic survival reflex."

from a paper entitled:  Respiration While Thumb Sucking and Without Thumb
Sucking, S. Mukai, C. Mukai, and S. Nagasugi.  Communicate with the authors
at:  The Department of Otorhinolaryngology, Mukai Clinic and Mukai Research
Institute of Biology, Yamatominami 2-8-9, Yamoto, Kanagawa, 242, Japan.

I suspect that these mid-line defects such as ADEL may not be the only
reason some infants switch to the "back-up" respiratory control during sleep
as a protection against apnea.  There may be other condidtions, as yet
undiscovered,  which constitute reasons why continuing to suck during sleep
may protect certain compromised infants.   And of course, sometimes a cigar
is just a cigar.  Some perfectly healthy kids may just like the sensation of
non-nutritive sucking.  I think the best thing about science is the give and
take and the constant reassessment of assumptions.  Just when I am
absolutely sure something is positively good or bad, somebody comes along
with a new idea and says:  Wait just a minute now.  Consider this!

Barbara Wilson-Clay, BSEd, IBCLC
Austin Lactation Associates
http://www.lactnews.com

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